Catalytic conversion



Patented July 29, 1952 ICE CATALYTIC CONVERSION Kenneth K. Kearby, Cranford, and James Black, Roselle, N. .L, assignors to Standard Oil Development Company, a corporation of Delaware No Drawing.

Thisinventi'on relates to the catalytic conversion of carbonoxides with hydrogen to form valuable synthetic products. More specifically, t .e inv'ention'is concerned with improved cataiysts and'rnethods of operation for the catalytic synthesis of normallyliquid hydrocarbons and oxygenated compounds from C and H2. The conventional hydrocarbon synthesis processes may be dividedinto two broad classes, depending on the type of catalyst used and the character of reaction products obtained. One class comprises reactions carried out at relatively low temperatures of about 350 450? F. and relatively low pressures of about 1-10 atm.,abs. in the presence of catalysts of which cobalt is a typical representative to form predominantly saturated parafiinic liquid and'solid hydrocarbons from which highly valuable diesel fuels and lubric'ating oils but only low octane number motor fuels may be obtained. The other class of processes employs iron type catalystsat higher temperatures of about 450-800 F. and higher pressures. of about 3-35 atm. abs. to obtain a predominantly unsaturated product from which "highly valuable motor fuels having satisfactory octane ratings may be recovered. Also in this class of processes, pressures of up to'lOO atms. or

higher may sometimes be used if high yields of oxygenated products are desired. The present invention is chiefly concerned with the high temperature',' high pressure reactions using iron type catalysts. Active iron catalysts are usually prepared by the, reduction of various iron ores or precipitated iron, oxides as well as by the decomposition of iron carbonyls; The catalytic activity of v the iron may be enhanced by the addition of such promoters as various compounds of alkali metals or the oxides of chromium, zinc, aluminum, magnesi um,,"manganese, the rare earth metals, and others, in small amounts/of about 1-10%.. It hasjalso been suggested to'deposit these iron catalysts in inert or active carriers such as siliceous materials, particularly kieselguhr, pumice, synthetic silica gel, or hydrated alumina.

The last-mentioned catalysts, that is those supported on carriers, have been found to be of particular interest in connection with synthesis reactions employing the .so-called fiuid catalyst technique wherein the synthesis gas is contacted with a dense turbulent bed of finely divided catalyst fluidized by the gaseous reactants and prod- I nets and which permits continuous catalyst replacementand affords a greatly improved'tem perature control of the highly exothermic and temperature-sensitive synthesis reaction. The adaptation of the hydrocarbon synthesis to the fluid catalyst technique has introduced a new factor in th rating of synthesis catalysts. total liquid yield as determined by activity (percent conversion) and selectivity (ratio 04+ higher hydro-carbons: Ci-lhigher Application'october 23, 1948,. Serial No. 56,248

6 Claims. (Cl. 2604.49.6)

hydrocarbons), olefin formation, and catalyst stability are theessential characteristics determining the utility of fixed bed synthesis cata1ysts;'the' fluid technique requires, in addition, ease of fluidization. None of the prior art catalysts complies satisfactorily with these requirements. Unsupported iron catalysts, while exhibiting high activity and selectivity, have poor fluidization characteristics mainly due to their high bulk density. Th known carrier catalysts have superior fluidzation characteristics but fall short with respect to activity and selectivity. This situation hasstimulated extensive research to develop a new type of synthesis catalyst of equal utility for fixed bed and fluid catalyst techniques. The presentinvention includes such a new development.

It is,therefore, a principal object of the present invention to provide a process for synthesiw ing hydrocarbons and oxygenated compounds from hydrogen and oxides of carbon in the presence'of an improved synthesis catalyst.

t is a more specific object of the invention to provide an improved hydrocarbon synthesis process carried out in the presence of a carrier catalyst having utility for both fixed bed and fiuid operation.

A further object of, the present invention is to provide a synthesis process of the type specified which is carried out in the presence of an improved iron type catalyst supported on a carrier material. I

Another object or" the invention is to provide means for improving the operational 1d efiiciency of the catalytic synthesis of high octane motor fuels from C0 and H2, employing the fluidcatalyst technique.

A still further object of the invention is to provide improved catalysts for hydrocarbon synthesis, having utility for both fixed bed and fluid operation.

Other and further objects and advantages will appear hereinafter.

tion of particularly active spinel-type compounds having the general While formula Me++Fe2+++O4, wherein Me++ is a bivalent non-iron metal and Fe+++ is trivalent iron. Bivalent metal components are, therefore, selected from those metals and metal compounds which, on the bases of their chemical and physical characteristics, are capable of forming spinel-type compounds with the oxide of trivalent iron. Examples for such bivalent 3 metals are Mg, Zn, Mn, Cd, the alkaline earth metals, Be, Cu, etc. Further, it has been found that best results are obtained when the bivalent metal component is present in proportions at form which, if desired, may be reduced with a reducing gas, preferably hydrogen, at temperatures of about 600-1800 F. Satisfactory results are obtained with catalysts containing, prior to least sufficient to convert the total amount of 5 reduction, from about or 20%, to 80%, prefertrivalent iron present into a, spinel-type comably about 30-80%, by weight of FezOa when pound. The bivalent metal component, therefore, magnesium oxide is the bivalent component, and i preferably used in amounts at least approachfrom about 5-65%, preferably 25-50% by weight ing or exceeding equimolecular proportions with of F6203 when zinc oxide is the bivalent comporespect to the trivalent iron oxide; larger amounts 1 nent. The proportions of F6203 in combination of bivalent metal component act as diluent or with other bivalent compo nts vary depending carrier without adversely affecting the activity on the molecular weights involved. Promoter and of the spinel-type combination proper; Thcrestabilizer may be added in proportions Varying fore, by using an excess of a bivalent component from 01-10% and 1-20%, respectively, based on giving a relatively low bulk density such as MgO, the composite catalyst. Excellent yields of valucatalysts of excellent utility for fluid solids operable liquid hydrocarbons have been obtained for ation may be prepared. example with a catalyst composed as follows:

The bivalent non-iron metals mentioned above P t give with trivalent iron oxide particularly when M O 6 5 4 used in spinel-forming proportions, composi 40 having a high synthesizing activity at least ap- 5 proximating and mostly surpassing that of pure K o 1 iron catalysts including magnetite which is a 2 naturally occurring iron spinel having the A typical method suitable for preparing catalysts formula Fe++Fe2+++O4=F3O4. However, paruseful'in the process is as follows: ticularly good results are obtained when using Magnesia is mixed with a solution of ferric Mg and/or Zn as the bivalent metal component.- nitrate. Ammonium hydroxide may be added to Materials comprising oxide composites of triensure complete precipitation. The magnesia valent iron with at least spinel-forming proporwith ferric hydroxide precipitate is washed. and tions of Mg and/or Zn, or reduction products of then mixed with solutions of copper nitrate and these oxide composites are, therefore, the prepotassium nitrate. The resulting mixture is ferred synthesis catalysts. As indicated above dried, molded into pills or lumps of any suitable the bivalent component of the catalyst may comsize and shape, roasted at about 1000'F., reduced prise oxides of one or more of the bivalent metals for about 4 hours at about 900 F. with about described, 1000 v./v./hr. of excess hydrogen and sintered The addition of a promoter and a stabilizer for about 4 hours at about 1200 F. in a non=oxigreatly enhances the activity of the catalysts. dizing atmosphere, for example of hydrogen. Preferred promoters are those obtained by the In carrying out the hydrocarbon synthesis in addition, to the original catalyst composite, of the presence of catalysts 0f the type above decompounds of potassium, such as KOH, K2003, scribed, conventional synthesis conditions for iron KNO3, KCl, etc. Similar compounds of other catalysts may be employed, for example temperaalkalis, such as Na, and Li, or of Ba and Ca, tures of about 450-800 F., preferably 500 700? as well as oxides of such elements as Al, Si, Cu, F., pressures of about 3-25 atm., HzzCo ratios of Mn or Cr may be added as promoters. Useful about 0.6:1-3zl, and space velocities of about 100- stabilizers may be derived from the oxides of 2500 v./v./hr., in either fixed bed or fluid bed metals of the right hand side (transition series) operation. In the latter case the catalysts may of groups I, II and III of the periodic system or have a particle size falling within the wide range certain non-acidic oxides. CuO has been found of 5-500 microns diameter while spheres of 5-200 to be particularly suitable for this purpose. The microns diameter are preferably used at superprincipal function of the promoter is to increase ficial gas velocities of 0.3-5 ft. per second. catalytic activity while the stabilizer is added to The superiority of the new type iron spinel prevent deactivation of the catalyst. catalysts over a pure iron catalyst such as the The catalysts may be prepared by methods of Fe++Fe+++ spinel magnetite in he absence of coprecipitation, impregnation, wet mixing, etc. carriersand promoters is illustrated by the typiin any conventional manner, followed by drying, cal experimental data listed in Table I below, pilling and roasting at temperatures of about which were obtained at optimum reactiont'e'm- 800-1600 F. to obtain the catalyst in the oxide peratures for the individual'c'atalysts- Table I IMOI FezOa-F lmolMgO' lmolZfiO .lmolCao lmol'FeO (MgFezOi) (ZI1F62Q4) r (OaFeQOi) (Magne't'i'te) (I) 900 (I) 900 (I) 900 88am Synthesis Gas Feed Rate, v./v./hr 200 200 20'0', 200 Synthesis Pressure, p. s. i.g 250 250 250- .1 250 Synthesis TempF 530 535 557 r 4 1 11:00 Volume Ration in Synthesis Feed Gas 1:1 1:1 1:1 1;1 V01. Percent CO2 in Exit Gas 48 49 4 r .29 Percent 00 Conversion 96 96 94 73 Measured Yield, (0. ctlcu. In. feed) 144 102 77 Yield; of C4 and Higher Hydrocarbons (c.c./cu.m.Hz+CO Consumed) 203 1'45- 142 1 Four hours with 1000'v./v./hr. excess H2.

The above data show that the spinel-type catalysts of this invention give a CO conversion which is more than 20% higher than that obtainable Catalyst I size Bulk Fluid), When using pure .iron spinel. Of particular I I Microns u v t importance are the high yields of liquid products I v produced by the zinc and magnesium=spinels 54% Mg0,40% a f n I which'surpass those of magnetite by:m0re than a usement;nausea;as; 20% and 40%,respectively. 50-60 79 o- As indicated above a further advantageof the 5132 312 Po o catalysts of the present inventionresides in the 10 Maunetite gig g i B fact thatthey may be supported on an excess of bivalent component to obtain supported catalysts 1 of highest activity suitable for the hydrocarbon h abpvfe table that h g i synthesis employing the fluid solids technique. ported spmel cata1y st P h mventlon hastlqe The data of Table 11 below illustrate the advan- 15 Same gogd charactenstflcs for-use in fluid catalyst tages of the use of the new catalysts over pro- Systems as other :3 0941113138 a d is in this cedures using iron catalysts supported on differrespect greafly'supenor to mm or lronoxlde ent carriers such as alumina,'silica microspheres, catalysts 9 of the spmel'type catalysts and silica-alumina microspheresand iron catasuppPrted m i t P of l lysts free of carrier material. A series of tests denslty have sumlar good flmdlty chaltaictenstlcs' carried out on such miscellaneous catalysts at has also been found .that the utmty of the 250 lbs/sq. in. pressure, 200'v./v./hr. space velocspmel'type catalysts descnbed above may b ity, and 0.8-4.1 HzzCOfeed ratio and optimum ther subsiialttlauy lmproved P I Y W reaction temperatures for the individual catalysts spect product select.lvlty and dlsmtegm' yielded the following results for fixed bed operanon fim the composltes tion: 5 p q are sub ected to fusion prior to use.

' Improved fused spinel-type catalysts in accord- Table H ance with the present invention may be obtained by preparing the promoted iron spinel composite '30 as described above, subjecting the dried composites to fusion, preferably in an electrical re- Ozgaldyst Oomposigtiogl Prior to Yured Liquid Temp" com, sistance furnace, cooling the melt and thereafter f g f l e and idge- 4 r. 2$, sizing and reducing the material as previously v pu i described. The component 'of the catalyst may I I 35 also be combined in the-fused state, for example :/b z %Q q 51 g V g the iron oxide may be fused, the spinel-forming g 7? 'iifixf ljg'zjfiga' 0 component admixed with the melt and the pro-.

I 72 #2 2 m0 er added either prior or after cooling. A 23%; ?238573 e e fzlgtfhfizj g typical method suitable for preparing catalysts Siica i p es I 39 I 70 4 of this type is as follows:

I 21 628 72 0 A solution of zinc and iron nitrates and a solu- F K91 139 96 tion of. sodium hydroxide were added simultaneously to water, maintaining a pH of 9-10. The 1 Estimatedfinal pH was adjusted to 6.5 with nitric acid. The l p 45 precipitate was filtered, washed, reslurried, filiFrom the above data-it will-be seen that the tered and washed. The cake was impregnated process carried out in the presence of a magwith a solution ofKzCOs, dried and calcined at nesia-supported iron-magnesia spinehcatalyst. 1600 F. Part of the catalyst Was electrically promoted with potassium and copper yields about fused by passing an electric current through the ,,'75% more liquid hydrocarbons :than the process mixture until a molten ingot was obtained. The using the most. active of the other carriercataingot was broken to provide particles of 4 to 12 lysts tested and closely approaches the yields mesh in size which were reduced for about 4 obtainable with pure iron oxide promoted with hours at about 900 F. with about 1000 v./v./ hr. KClJ 1 of excess hydrogen. I I

; Fluidity tests carried out in a 1 /8" Vycor tube The high activity and selectivity ofthe fused using H2 or N2 as the fiuidi'zing'gas at superficial 'spinel-type catalysts just described is" illustrated velocities of 0.3-0.5 ft. per second gave the folby the comparative fixed bed single pass test data lowing results: reported below. I

Table IV Not Fused Fused 23. at; v; has a 3 91: its. Promoter ace K20 2% K2003 2% K2003 2% K2003 H: CO Ratio 2: Feed Rate, v 200 Pressure, 1). s. i. g... 2 Temperature,F I 520 650 CO Conversion, Percent 94 95 94 95 94 96 O4+Yield, c. c./cu. m. HrI-CO Consumed 197 193 19c 200+ 17o It will be observed that particularly the fused ZnO and MgO spinels compare very favorably with the corresponding unfused spinels with respect to CO-conversion and liquid product yields aware.

This application is a continuationin part of ourcopending application Serial No. 637,100fi1ed D'ecember22', 1945, now abandoned.

'Thepres'e'iit'invention is not to be limited to any theory of the mechanism of the process or catalysts nor 'to any e'x'amplesjgiven merely for illustrative purposes, but'only: by the following TWhat is claim'eol'isjz. J

"I. irhproved'pi'o'css for producing valuable conversion products from C and H2 by a; catalytic synthesis reaction which comprises contactinga gas co'htainirigfCO- and' H2 in proportions and at conditions. conducive to the formation of normally liquidhydroca'rbons' With a dense, turbulent, fluidized mass of finelydivide'dcatalyst consisting essentially of a combination of at least 7 aboutweight per cent of a trivalent iron component, calculated on an oxide basis, with at least about an equimoleciilaifamount of a bivalent metal component capable. of forming a spinel type compoundselcteii from the goup consisting of the oxygen compounds of magnesium and zinc, saidflca-talys t being obtained by subjecting a compcsite theoxide analysis ofwhi'c'h a proximates 54% MgO, about 40% 'FezOa, about 5% C119 and about 1% K to a reducing treatment with hydrogen at temperatures of about 600 to 2. An'improved-process for producing valuable conversion products from C0 and H2 by .acatalytic synthesis reaction which comprises' contactinga gas containing CO and H2111 synthesis proportions at synthesis conditions with. a dense turbulent fluidized mass of finely divided catalyst consisting essentially of an originally fused and reduced composite of at least about 5 weight'per cent of a trivalent iron component calculated on an oxide basis and at least about an equim'olecular amount of a bivalent metal component capable'of forming a spine] type compound selected from the. group consisting of magnesium and zinc, promoted with a 'minor amount of an alkali metal compound promoting the selectivity of the catalyst to normally liquid products.

3. The process of claim 2 in which said alkali metal is potassium.

'4. The processof claim 2 in which said catalyst is obtained by a method comprising combining the trivalent ir'on component with the bivalent metal component and the alkali metal compound,- fusing the combined product, cooling, sizing andv reducing the fused material.

5. The process of claim 2 in which said combined productis calcined prior tofusing.

6. The process of claim 2 in which said catalyst is obtained by a method comprising fusing the trivalent iron component, adding the bivalent metal component to the melt, cooling and sizing the combined product and reducing the sized material in the presence of the alkali inetal com pound.

KENNETH K. KEARBY. JAMES F. BLACK.

REFERENCES CITED The following references are of record in the file of this patent:

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1. AN IMPROVED PROCESS FOR PRODUCING VALUABLE CONVERSION PRODUCTS FROM CO AND H2 BY A CATALYTIC SYNTHESIS REACTION WHICH COMPRISES CONTACTING A GAS CONTAINING CO AND H2 IN PROPORTIONS AND AT CONDITIONS CONDUCIVE TO THE FORMATION OF NORMALLY LIQUID HYDROCARBONS WITH A DENSE, TURBULENT, FLUIDIZED MASS OF FINELY DIVIDED CATALYST CONSISTING ESSENTIALLY OF A COMBINATION OF AT LEAST ABOUT 5 WEIGHT PER CENT OF A TRIVALENT IRON COMPONENT, CALCULATED ON AN OXIDE BASIS, WITH AT LEAST ABOUT AN EQUIMOLECULAR AMOUNT OF A BIVALENT METAL COMPONENT CAPABLE OF FORMING A SPINEL TYPE COMPOUND SELECTED FROM THE GROUP CONSISTING OF THE OXYGEN COMPOUNDS OF MAGNESIUM AND ZINC, SAID CATALYST BEING OBTAINED BY SUBJECTING A COMPOSITE THE OXIDE ANALYSIS OF WHICH APPROXIMATES 54% MGO, ABOUT 40% FE203, ABOUT 5% CUO AND ABOUT 1% K2O TO A REDUCING TREATMENT WITH HYDROGEN AT TEMPERATURES OF ABOUT 600* TO 1800* F. 